Achondroplasia, an inherited genetic condition, affects the fibroblast growth factor receptor in the body. This protein develops abnormally and slows down bone growth in the growth plate cartilage. Individuals with achondroplasia suffer from shorter, poorly formed bones which result in a dwarfed physical stature. Adult heights for individuals with achondroplasia range from 42 to 56 inches.

Achondroplasia occurs due to a lack of cartilage conversion to bone (known as ossification). The FGFR3 gene is responsible for this disorder, contributing to the production of collagen and other key components in tissues and bones. Upon mutation in the FGFR3 gene, the production of growth factors that interfere with bone production is impaired. This leads to an obstruction in the development of cartilage, causing the person to be disproportionately shorter in height.

A naturally inhibitory gene that affects bone growth, FGFR3 gene capability alters in achondroplasia resulting in shorter bones. Advanced paternal age may be linked to sporadic achondroplasia, with most affected patients having no family history. Familial (inherited) cases of achondroplasia indicate an autosomal dominant inheritance pattern. A dominant genetic disorder requires just one copy of an abnormal gene to cause the issue. The risk of passing this genetic mutation is 50% for each pregnancy, irrespective of gender, where the gene may be inherited from either parent or result from a mutation in the affected person.

Over 80% of cases of achondroplasia develop due to spontaneous mutations. Healthy parents with no family history of the disorder are capable of giving birth to a child with achondroplasia. In contrast, at least one affected parent has a relation to the remaining 20% of achondroplastic cases.

References:

- https://medlineplus.gov/genetics/condition/achondroplasia

- https://www.hopkinsmedicine.org/health/conditions-and-diseases/achondroplasia

- https://www.ncbi.nlm.nih.gov/books/NBK559263/

- https://en.wikipedia.org/wiki/Achondroplasia